Adjustable protractor



Jan. 10, 1933. w. LUCK 1,894,107

ADJUSTABLE PROTRACTOR Fild Dec. 27, 1930 Patented Jan. 10, 1933 UNITED STATES WILLIBALD LticK, or new YORK, N. Y.

ADJUSTABLE PROTRACTOR Application filed December 27, 1930. v Serial No. 505,047.

The main object of this invention is to provide a protractor having two arms thereon by which angles of opposing quadrants may be scribed.

Another object of the invention is to provide a combination measuring rule and adjustable protractor which is provided with a pair of arms arranged at right angles to each other and provided at their intersection with means which, in combination with a rotatable dial, indicates two angles of complementary quadrants.

The above and other objects will become apparent in the description below in which characters of reference refer to like-named parts in the drawing.

Referring briefly to the drawing, Figure 1 is a perspective view of the protractor showing one of the arms at a position at right angles to the body of the rule.

Figure 2 is a fragmentary perspective view of a portion of the rule and protractor arms.

Figure 3 is a longitudinal sectional elevational view through the protractor arm and body of the rule.

Referring in detail to the drawing, the

numeral 10 indicates a fiat longitudinal squared bar which is provided with a straight edge 11. The upper face of the bar or rule 10 is provided with a linear series of graduations 12 which are divided into inches, each of the latter being indicated by its numerical equivalent 13. The opposing side of the rule or bar has formed thereon a longitudinal recess 14 which extends throughout the greater portion of the length of the bar. Centrally of the length of the bar, an opening 15 is formed. This opening receives the shank 16 of a stud which has a thread 17 at its extremity and intermediate its length is provided with a shoulder 18. The head 19 of this stud passes through the material at the intersection of a pair of protractor arms 20 and 21 which are arranged at right angles to each other and also are provided with inch graduations 22 as is the body 10 of the rule. The shank 16 projects above the face of member 10 and upon the shoulder 18 a dial disk 23 is anchored. The stud is rotatable with the arms 20 and 21. Beneath the dial 23 a split dished-out spring 241 is located around the stud 16 and is adapted to cooperate with a knurled thumb nut 25 to frictionally retain the protractor arms 20 and 21 in any desired adjusted position. The car 26 of a pointed 5 indicator bracket 27 is imbedded in the body 10 directly above the dial, and is adapted to point to the arcuate graduations 28 formed on the face of the dial. To reinforce the intersecting positions of the arms 20 and 21 0 where these two members merge, a metallic plate or angle iron 29 is imbedded in a slot in the intersecting ends of these arms. The angle iron 29has a sleeve 30 secured thereto in which the stud 16 is rotatably mounted.

The device is adapted to serve as a protractor for scribing various angles of an 180 arc. The one arm 21 is adapted to scribe any are within a 90 radius while the opposing arm 20 of the protractor is adapted to scribe any arc in the complemental quadrant of 90. The bar 10 may also be used as a measuring element for attaining linear dimensions upon a sheet of drawing or the like. The line 31 v extending longitudinally and centrally through the bar 10 indicates the axis of the bar, and this line must be held parallel with the line of the layout about which the angle is to be drawn. The stud 16 is firmly im bedded in members 20 and 21 at the intersec- '80 tion thereof. The arms 20 and 21 as previously stated embrace an area of two complemental quadrantsand are rotated simultaneously with the dial 23 which is graduated, arcuately to indicate various predetermined angles which graduations 28 may be indicated by angle characters not shown on the drawing. The stud moves with the arms 21 and 20 and the dial 23, being mounted on the square end of the stud 16, also rotates witheo the arms and indicates the angle desired through the medium of the index 27. This device may conveniently rest upon a drafting table or the like as the protractor arms 20 and 21 fit alternately into the recess 14 which is formed in the bar or rule 10.

It is to be noted that certain changes in form and construction may be made without departing from the spirit and scope of the invention. 1

' I claim:

1. In a device of the class described, a linear graduated rule having a longitudinal recess therein, a pair of intersecting protractor arms joined at right angles to each other, a stud secured to said protractor arms at the axial intersection thereof, said stud passing through said rule and being rotatable therein, said stud having a shank thereon, an an- 10 nular dial mounted on said shank, said dial having radial graduations thereon, and means on said rule cooperating with said dial for visibly indicating the adjusted angle of either of said arms.

2. In a device of the class described, a linear graduated rule having a longitudinal recess therein, a pair of intersecting protractor arms joined at right angles to each other, a stud secured to said protractor arms at the axial intersection thereof, said stud passing through said rule and being rotatable therein, said stud having a shank thereon, an annular dial mounted on said shank, said dial having radial graduations thereon, an index on said rule cooperating with said dial for indicating the adjusted angle of said protractor arms, said stud having a threaded extremity projecting above said dial, a spring washer beneath said dial resting on said rule,

and a thumb nut threadably engaging said stud for yieldably flattening said spring washer to frictionally retain the protract-or arms in adjusted position.

In testimony whereof I afiix my signature.

WILLIBALD LUCK. 

